Just out of interest then...suppose we've got a loopback swap deviceand that we can extend this by creating a new file or extendingsomehow the existing one.

What would be wrong with having the page reclaim algorithms use one ofthe low memory watermarks as a trigger to call in to userspace toextend the swap available if possible? This is probably what Microsoftet al do with their "Windows is extending your virtual memory, yadayada blah blah". Comments? Already done?